What is the Biological Cycle?

You have probably been asked “Is your tank cycled?” when you have come in to purchase tropical fish at Aquariums West and wondered what the heck is that. “Was I supposed to have remembered this from high school?” Many people have lost many fish because they do no understand what this is. People who have had aquariums for years with lots of experience still try to buy fish when they are in the middle of the cycle. The truth is that they just keep replacing fish that die without ever wondering why. We want you to be successful and we don’t want your fish to die. These creatures have traveled half way around the world to get into your aquarium. Some of them can live a very long time if they are treated well. (Read How Long Do They Live?)

Follow these simple guidelines listed below to go through the Biological Cycle or Nitrogen Cycle in a Fresh Water Aquarium.

1.) Put in only a small amount of fish in the beginning with lots of aquatic plants. No more then 1 small fish for every two gallons of water. Ask your tropical fish specialist which fish are appropriate for the size of your aquarium. Why the plants? They create a natural environment, add oxygen to the water, absorb ammonia, nitrite, nitrate, phosphate and help lessen the effects of the Cycle.

2.) Add a Bio Starter (biological bacteria) product such as Hagen’s Cycle or Seachem’s Stability to the water (follow the instructions on the package). These products speeds up the cycle. If you are patient you can forgo the Bio starter and wait 30-45 days before adding more fish. Only add a few fish at a time.

3.) Feed your fish only once a day a small amount that they will consume in 5 minutes. If there is any left over food hanging around on the bottom of the aquarium, you have fed too much. Try to scoop it out with your fish net or do a water change.

4.) Do a 1/3 water change after two weeks to dilute the ammonia and nitrite levels. Tip – Keep your pH below 7.0 during the cycle as ammonia is converted to the less toxic form called ammonium at a lower pH.

5.) Test the pH, ammonia, nitrite and nitrate levels of your aquarium or bring in a water sample and we will do it for you. If the levels are normal your tank has completed the Biological Cycle. Congratulations, you can now add a few more fish.

But what exactly is the Biological cycle?

The biological cycle in an aquarium is the formation of beneficial bacteria that will help keep your tank healthy and balanced. When you introduce fish into a new aquarium, there is very little bacteria – as far as the fish are concerned the tank is pristine and clean. Almost immediately, your fish will begin to eat and produce waste.This waste doesn’t magically disappear into space but exists in your filter, on the bottom of the aquarium and on the rocks and plants. It begins to break down and rot. One of the bi-products of this is ammonia, which comes from fish respiration as well as decomposing organic waste such as left over food particles. What you want to avoid is such a swift increase in ammonia (because of over feeding and over stocking of your aquarium) to cause toxic levels of ammonia. Ammonia exists in the form of a gas and gets into the fishes bloodstream just like oxygen. When the levels are in excess your fish are actually suffocating, extremely uncomfortable and vulnerable to infections and disease. Not a pretty sight. You want this natural increase in ammonia to be gentle, so that the fish can adjust to it gradually.

The beneficial bacteria that we need to culture in the aquarium are called Nitrosomonas and Nitrobacter bacteria. Nitrosomonas Bacteria break down the deadly ammonia to a less toxic nitrite. Nitrobacter bacteria then converts nitrite to an even less toxic nitrate. These bacteria are required to break down the waste and excess food and render it harmless. By not overloading your aquarium with too many fish and too much food you don’t create an excessive amount of ammonia. This process usually takes 4 – 6 weeks if you let nature take it course. You can speed things up by adding Seachem Stability for the first ten days of introducing fish into your aquarium and can cycle in as little as 10 – 14 days. Another product on the market that encourages the nitrosommonas bacteria to multiply, is Hagen’s Cycle. Both Cycle and Stability are available at Aquariums West.

You can purchase an ammonia, pH, nitrite and nitrate test kit to monitor where you are with regards to the cycle or bring in a sample of water (1/2 cup to allow for spillage) and we will test it for you.

Remember that patience is the number one ingredient when beginning a new aquarium.

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